Crossref Metadata Search

About Crossref Metadata Search

The Crossref REST API provides programmatic search and retrieval of bibliographic metadata deposited by Crossref member publishers, including records and their associated Digital Object Identifiers (DOIs). Records typically become available through the API within 20 minutes of deposit, and aggregate information such as counts is processed in batch every 24 hours.

The API is public and free to use, requiring no API tokens or registration. Users are asked to follow etiquette guidelines: caching data to avoid redundant requests, monitoring response times and backing off when they increase, and specifying a User-Agent header with contact information (including a "mailto:" email). Clients that connect via HTTPS and provide contact information in the User-Agent header or as a query parameter are routed to a separate pool of machines reserved for polite users, offering more reliable service; this policy has been in effect since September 18, 2017.

This particular repository documents the older Solr-based version of the API and is marked deprecated; current documentation is maintained at api.crossref.org, with issues reported via the community forum or support email. Several third-party client libraries exist for languages including Python, Ruby, R, Rust, and Julia. The service is intended for developers building tools that search or reuse scholarly metadata, such as bibliography managers or citation tools.

Key features

• Search and retrieve members' bibliographic metadata and DOIs via a REST API
• New records appear in the API within about 20 minutes of deposit
• Field queries, filters, facet counts, and sorting for refining search results
• Free public access with no API tokens or registration required
• Polite pool of dedicated machines for HTTPS requests with contact info for more reliable performance
• Official client libraries available in Python, Ruby, R, Rust, and Julia

Frequently asked questions